1. Field of the Invention
The present invention relates to a sheet binding processing apparatus to bind a plurality of sheets, and relates to improvement of a binding mechanism.
2. Description of Related Arts
In general, such a kind of the binding processing apparatus has been known such as a post-processing apparatus in an image forming system to perform a binding process on a sheet bundle that is supported on a sheet placement base (sheet supporting face). There have been known, as a binding processing mechanism, a mechanism to bind a sheet bundle using a staple (staple binding mechanism) and a mechanism to perform pressure-contact binding on a sheet bundle as pressure-nipping the sheet bundle with pressurizing faces having concave-convex faces (pressure-contact binding mechanism).
The pressure-contact binding mechanism to perform a binding process on a sheet bundle without using a metal staple has been adopted as a binding method that enables the bound sheets to be easily separated to prevent an environmental problem from occurring at the time of document disposal. However, there has been known a problem that sheets are unbound when the sheet bundle is thick, when turning a page rapidly, and the like.
For example, Japanese Patent Application Laid-open No. 2012-47940 proposes an apparatus to perform binding by deforming a plurality of sheets into a corrugation shape in cross-section while tooth forms having a convex shape and a concave shape are formed at a pair of pressurizing members that presses the sheet bundle.
The document discloses a pressurizing mechanism in which a plurality of tooth forms are arranged in line with a tooth width direction being oriented from a sheet center side toward an end edge side.
Further, Japanese Patent Application Laid-open No. 2010-274623 discloses a mechanism in which a plurality of tooth forms having different pressurizing engagement shapes arranged in a replaceable manner and performs binding on a sheet bundle with an engagement shape in accordance with a bundle thickness.